Process for the production of alpha-amino-2-hydroxy-phenylacetic acids

ABSTRACT

Alpha -Amino-2-hydroxyphenylacetic acids which are known intermediates for the preparation of various antibiotics are prepared from 2-hydroxyphenylacetic acid lactone through nitrosylation, catalytic hydrogenation in the presence of an alkanoic acid anhydride and hydrolysis with aqueous mineral acid.

United States Patent 1 Oediger et a1.

[ PROCESS FOR THE PRODUCTION OF ALPHA-AMlNO-Z-HYDROXY- PHENYLACETIC ACIDS [75] Inventors: Hermann Oediger, Cologne; Rudolf Braden, OdenthaLScheuren. both of Germany Bayer Aktiengesellschaft, Leverkusen, Germany [22] Filed: Nov. 30, I972 [21) App]. No.: 310,792

[73] Assignee:

1 1 Apr. 29, 1975 FQREIGN PATENTS OR APPLICATIONS 2.162.717 6/1973 Germany 260/519 OTHER PUBLICATIONS Chemical Abstracts, Vol 68, 95624x, (1968) and Formula Index-C811 5NO3.

Primary E.ram[ner-Lorraine A. Weinberger Assistant Examiner-Patrick .l. Hagan [57} ABSTRACT a-Amino-2hydroxyphenylacetic acids which are known intermediates for the preparation of various antibiotics are prepared from Z-hydroxyphenylacetic acid lactone through nitrosylation, catalytic hydrogenation in the presence of an alkanoic acid anhydride and hydrolysis with aqueous mineral acid.

6 Claims, No Drawings PROCESS FOR THE PRODUCTION OF ALPHA-AMlNO-Z-HYDROXY-PHENYLACETIC ACIDS DETAILED DESCRIPTION The coumaranedione-monoxime of Formula III is next catalytically hydrogenated in the presence of an acid anhydride of the formula:

5 The present invention relates to a process for the pro- R .CQ\ duction of a-amino-2-hydroxyphenylacetic acids. IV which are known as intermediates for the synthesis of 2 pharmaceuticals. particularly certain antibiotics. as dis- R cussed below. It! h It is known that ot-amino-2-hydroxyphenylacetic acid m can be obtained bv converting 2-methoxvhenzaldehyde R R are the same or different alkyl group of 1 to 4 carbon atoms mto the corresponding hydantoin with potassium cyanide and ammonium carbonate. demethylating this to New 8 B'umldocoumamnonfl of the fmmulu: with hydriodic acid by heating. and saponifying the rel sulting 5-( Z-hydroxyphenyll-hydantoin with barium 0 hydroxide; see. eg J. Org. Chem. 9 (1944). ll. The 0 total yield however. is less than so that this process i 1 V is uneconomical in this regard. Furthermore. hydriodic acid is expensive when employed industrially Finally. saponification with barium hydroxide is a complicated procedure since barium ions have to be removed. for This 3 dmidocoumamnone is finally hvdmlvzed with example as the sparingly soluble sulphate. before isolatdilue mineral acid to produ'ce desired ing h 9 phmmuciutlcul mtermcdime" a-amino-2-hydroxyphenvlacetic acid of Formula I.

This invention now provides a process for the pro- Whik2 it is known phcnvlacetic acid ethyl ester duction of oz-amino-Z-hydroxyphenylacetic acids ofthe can be Cmwcrmd into the mximino derivative with fmmuh: 0H ethyl nitrite in the presence of potassium ethylate; see e.g. Ber. d. dtsch. Chem. Gesellschaft. Vol. 42 (1909 I 30 page 19.30. the process is technically complicated. CH QOOH Arylacetic acid ethyl esters in general have little tendency to react with nitrous acid; see e.g. Houben-Weyl- R NH Muller. Vol. X/4. page 29. In contrast Z-hydroxy- 2 phenylacetic acid lactone reacts with nitrosylating in which R is hydrogen. halogen or alkyl of l to 4 car- 1 agents i an acid medium smumhh-q rapidly d i hi h i yield to yield the coumaranedione-monoxime.

Accmdmg pl'cscm P l' The individual reaction steps of the process accord- Phcnylaccllc lllcmm of the formula: ing to the invention are technically simple to carry out 0 and good yields are realized in each step. The

4 wamino-Z-hydroxyphenylacetic acids are thus oh- II tained in higher yields than according to the known process. In addition. the process permits the product to R be produced industrially in a highly economical manis reacted with nitrous acid. or a derivative of nitrous I acid, in a solvent to produce a coumaranedione-3- 45 for example z'h-vdmxyphenylaenc lq hicwne monoximc of thc thrmulu: is used as the starting substance. sodium n trite in glao cial acetic acid is used as the donor of nitrous acid. acetic anhydride is used as the alkanoic acid anhydride. palladium-on-charcoal is used as the hydrogenation III catalyst and hydrochloric acid is used as the hydrolyz- NOl-l I ing mineral acid, the course of the reaction can be dia- R grammatically depicted as follows:

Y w 1 l 2 j *3 ca coou 1% xsoa Pd-C/ H (CH C0) 0 V 0H 0 G O Y CH-COOH NH-i-Cll i NH 0 The 2-hydroxyphenylacetic acid lactones which are used as starting materials for the process according to the invention are either known or can be produced according to known processes. for example by splitting off water from the corresponding 2-hydroxyphenylacetic acids; see e.g. J. Amer. Chem. Soc. 82 (1960). 2035v The nitrous acid derivatives which are used in the first stage of the reaction include lower alkyl esters. alkali metal salts and the chloride of nitrous acid. Lower alkyl esters are those alkyl esters having up to 6 carbon atoms. such as methyl nitrite. ethyl nitrite. n-butyl nitrite. amyl nitrite and the like. Sodium nitrite is particularly suitable for use as the alkali metal salt of nitrous acid. Nitrosyl chloride can also be used. Solvents for the reaction include ethers such as diethyl ether and aliphatic carboxylic acids having up to 6 carbon atoms as for example acetic acid and propionic acid. An acidic environment is advantageous. If nitrous acid esters are used in a neutral solvent. for example ether. hydrogen chloride is thus generally introduced into the reaction mixture in order to initiate the nitrosylation. A preferred combination is sodium nitrite in glacial acetic acid.

Typically. 1 mole of the Z-hydroxyphenylacetic acid lactone is reacted with 1.5 moles of the nitrous acid derivative. a larger excess of the nitrosylating agent doing no harm. It is often advantageous to use a one molar to two molar excess if sodium nitrite is employed. Reaction temperatures can range from about -l to about +3(lC. especially from about l0 to about C. The coumaranedione-monoxime solidifies as a precipitate and can be isolated by filtration if desired.

The coumaranedione-monoxime is then catalytically hydrogenated in the presence of an acid anhydride. The coumaranedione-monoxime can be employed in the crude form obtained in the first stage or in purified form. The hydrogenation can be conducted in a polar solvent such as an ether. for example dioxane. tetrahydrofuran or ethylene glycol dimethyl ether; dimethylformamide. tetramethylenesulfone. N- methylpyrrolidone. or an aliphatic carboxylic acid hav ing up to 6 carbon atoms such as acetic acid or propionic acid. Mixtures of solvents can also be used. Cat-a lysts which can be used include Raney catalysts such as Raney nickel or noble metal catalysts. for example palladium or platinum catalysts which can be precipitated on the customary supports. Supported palladium contact catalysts such palladium-on-charcoal. aluminium oxide or barium sulfate are particularly suitable. Preferred acid anhydrides of Formula IV are the anhydrides of lower aliphatic carboxylic acids with 2 to 4 carbon atoms. such as acetic anhydride and propionic anhydride. Acetic anhydride is preferably used but the nature of R and R is not critical.

The reaction temperatures are generally between about 20 and about 100C. especially from about 50 to about 80C. Although the hydrogenation can be conducted at atmospheric pressure. it is preferably carried out at pressures of from about 5 to about 100 bars. preferably 40 to 60 bars. of hydrogen.

The amidocoumaranone which is obtained in the second stage, is isolated by removing the catalyst. evaporating the solvent. and purifying the reaction product by trituration with a solvent in which it is sparingly soluble. such as ethyl acetate or diethyl ether.

The resulting amidocoumaranone of Formula V is then hydrolyzed with an aqueous mineral acid such as hydrochloric acid. hydrobromic acid or sulfuric acid. The concentration of the acid is not critical and can vary from about UN to about lON. depending on the acid. Preferably. the concentration is between 2 and 4N. Typically. 1 mole of the corresponding amidocoumaranone is hydrolyzed with at least 2 moles of acid. Reaction temperatures are generally from about 60 to about 120C. preferably to l00C. The reaction time depends on the temperature. At 90C. it is about 4 hours. Above C. the reaction can be carried out under pressure. The solution resulting from hydrolysis is concentrated in vacuo and neutralized with an aqueous alkali metal hydroxide solution. such as potassium hydroxide solution. sodium hydroxide solution. or with ammonia. The a-amino-2-hydroxyphenylacetic acid is obtained directly in a highly pure form. It can. if desired. be purified further as by recrystallization. for example from water.

The product produced by the process of the invention is asymmetric and can be resolved into its optical antipodes by conventional means. e.g. salt formation with camphorsulfonic acid or other optically active acids.

The a'aminohydroxyphenylacetic acids thus produced are suitable for the manufacture of certain antibiotics. including the cephalosporin derivatives of Canadian Patent Specification 873,869. in addition. the a-amino-Z-hydroxyphenylacetic acid can be used to convert b-aminopenicillanic acid into the highly active penicillin. 6-(a-amino-2-hydroxyphenyl acet amido)- penicillanic acid through any of the well known acylation techniques. Since the pencillin formed with the R- form of a-amino-2-hydroxyphenylacetic acid is outstandingly effective. resolution as described above is preferably performed before acylation.

The following examples will serve to further typify the nature of this invention without being a limitation on the scope thereof. the scope being defined solely by the appended claims.

EXAMPLE 1 a-Amino-Z-Hydroxyphenylacetic Acid A. To a solution of [34 parts by weight of 2-hydroxyphenylacetic acid lactone in l000 parts by volume of glacial acetic acid are slowly added 2l0 parts by weight of sodium nitrite at l0 to 20C. The reaction mixture is stirred for four hours at 15 to 20C and is subsequently poured into 3 litres of ice water. The reaction product is collected by filtration. washed with water and dried over potassium hydroxide to yield I40 parts by weight of coumaranedione-3-monoxime. m.p. l76l82C (dec).

B. A solution of I47 parts by weight of coumaranedione-3-monoxime in 450 parts by volume of glacial acetic acid and 450 parts by volume of acetic anhydride is catalytically hydrogenated with 15 g of 5% palladium-on-charcoal at 60C under a pressure of 40 to 60 bars of hydrogen. The catalyst is removed by filtation. the filtrate is evaporated and 1 18 parts by weight of 3-acetamidocoumaran-Z-one are obtained by triturating the evaporation residue with ether. m.p. l77-l82C (dec).

C. Ninety-six. parts by weight of 3- acetamidocoumartin-Lone are hydrolyzed with 1300 parts by volume of 3N hydrochloric acid for 4 hours at 95C. The solution is concentrated to approximately 300 parts by volume and rendered neutral to Congo Red with concentrated ammonia solution. The a-amino-Z-hydroxyphenylacetic acid which thus solidifies is collected by filtration, washed with water and dried in vacuo at 70C. The yield is 65 parts by weight. melting point: l90-l9lC (dec).

EXAMPLE 2 3-monoxime in 500 parts by volume of dioxane and l50 parts by volume of acetic anhydride are catalytically hydrogenated with 5 g of 571 palladium-oncharcoal at 70 to 80C in a fashion analogous to that described in Example lB to yield 31.] parts by weight of 3-acetamido-5-chlorocoumaranone, m.p. l97l99C (dec).

C. A mixture of 22.5 parts by weight of 3-acetamido- 5-chlorocoumaran-Z-one. 267 parts by volume of 3N hydrochloric acid and 200 parts by volume of dioxane are heated under reflux for 4 hours. The solution is evaporated and the residue is taken up in a 4 fold amount of water and treated with 50 parts by volume of 2N sodium hydroxide solution. The a-amino-2- hydroxy-S-chlorophenylacetic acid which solidifies is collected by filtration, washed with water and dried to yield l7.8 parts by weight of product. m.p. l86-l87C (dec).

In a similar fashion, a-amino-2-hydroxy-5- methylphcnylacetic acid is obtained from 2-hydroxy-5- methylphenylacetic acid lactone.

What is claimed is:

l. A process for the preparation of an a-amino-2-hydroxyphenylacctic acid of the formula:

ca-cooa R l Ill wherein R is hydrogen. halogeno or alkyl of l to 4 carbon atoms, which comprises nitrosylating a Z-hydroxy phenylacetic acid lactone of the formula:

wherein R is as defined above, at a temperature of from about l0 to about 30C. in an acidic environment with a lower alkyl ester, an alkali metal salt or the chloride of nitrous acid, to yield the corresponding coumaranedione-3-monoxime: catalytically hydrogenating said coumaranedione-B-monoxime in the presence of an alkanoic acid anhydride of the formula R'COOCOR in which R and R are independently alkyl groups of l to 4 carbon atoms, to yield a 3- amidocoumaran-Z-one of the formula:

Ill-IGOR" wherein R is as defined above; and hydrolyzing said 3- amidocoumaran-Z-one with aqueous mineral acid.

2. The process as defined in claim 1 wherein said 2-hydroxyphenylacetic acid is nitrosylated with sodium nitrite in glacial acetic acid.

3. The process as defined in claim 1 wherein the catalyst for said hydrogenation is a supported palladium contact catalyst.

4. The process as defined in claim 1 wherein the alkanoic acid anhydride is acetic anhydride and R is methyl.

5. The process as defined in claim 1 wherein the hydrolysis of said 3-amidocoumaran-2-one is effected with an aqueous mineral acid having a concentration of 2N to 4N.

6. The process as defined in claim 1 wherein Z-hydroxyphenylacetic acid lactone is nitrosylated with sodium nitrite in glacial acetic acid at a temperature of from about l0 to about 20; the coumaran-2.3-dione- 3-monoxime thereby obtained is hydrogenated in the presence of acetic anhydride over a supported palladium contact catalyst; and the 3'acetamidocoumaran- Z-one thereby obtained is hydrolyzed with an aqueous mineral acid having a concentration of 2N to 4N to yield a-amino-2-hydroxyphenylacetic acid. 

1. A PROCESS FOR THE PREPARATION OF AN A-AMINO-2HYDROXYPHENYLACETIC ACID OF THE FORMULA:
 2. The process as defined in claim 1 wherein said 2-hydroxyphenylacetic acid is nitrosylated with sodium nitrite in glacial acetic acid.
 3. The process as defined in claim 1 wherein the catalyst for said hydrogenation is a supported palladium contact catalyst.
 4. The process as defined in claim 1 wherein the alkanoic acid anhydride is acetic anhydride and R1 is methyl.
 5. The process as defined in claim 1 wherein the hydrolysis of said 3-amidocoumaran-2-one is effected with an aqueous mineral acid having a concentration of 2N to 4N.
 6. The process as defined in claim 1 wherein 2-hydroxyphenylacetic acid lactone is nitrosylated with sodium nitrite in glacial acetic acid at a temperature of from about 10* to about 20*; the coumaran-2,3-dione-3-monoxime thereby obtained is Hydrogenated in the presence of acetic anhydride over a supported palladium contact catalyst; and the 3-acetamidocoumaran-2-one thereby obtained is hydrolyzed with an aqueous mineral acid having a concentration of 2N to 4N to yield Alpha -amino-2-hydroxyphenylacetic acid. 